The present invention relates to braking systems for road vehicles, especially braking systems including an eddy current brake for generating eddy currents to retard the rotation of a vehicle""s axle.
Eddy current braking systems typically include a rotor mounted to a rotatable shaft, such as a vehicle axle and a magnetic power source, such as an electromagnet or a permanent magnet fixed to a vehicle frame. Eddy currents are produced in the rotor due to a relative velocity difference between the rotor and the stationary magnetic power source. The eddy currents generate a braking force retarding the rotation of the rotor, thereby decelerating the vehicle.
While prior art eddy current braking systems achieve their intended purpose, many problems still exist. For example, prior art eddy current braking systems typically, are unable to generate the required braking torque to stop a vehicle, hence these systems are only used in conjunction with conventional friction brake systems. Thus, conventional eddy current braking systems add significant cost to the vehicle without providing significant improvements in brake performance, reduction in brake wear and an increase in customer satisfaction.
Therefore, there is a need for a new and improved eddy current braking system for a motor vehicle. The new and improved eddy current braking system should be capable of generating the total required braking torque to bring a motor vehicle to rest, such that the eddy current braking system is able to replace conventional frictional braking systems.
In an aspect of the present invention, an eddy current brake or retarder device for bringing a vehicle to rest is provided. The device includes a stator, a plurality of poles, a plurality of coils, and a rotor. The stator is mounted to a frame of the vehicle. The plurality of poles are disposed along a perimeter of the stator. The plurality of coils wherein each of the plurality of coils are wound about each of the plurality of poles. Moreover, an adjacent pair of poles are electrically connected to form an electromagnet when the coil is energized. The rotor is in communication with a transmission axle of the vehicle and located concentric with the stator, and wherein a relative rotation of the rotor with respect to the stator produces eddy currents between the poles of the stator and an outer surface of the rotor, causing the rotor to come to a rest.
In another aspect of the present invention, an end plate is located at an end of each of the plurality of poles.
In another aspect of the present invention, the end plate has a plurality of grooves disposed in a top surface of the end plate to form a plurality of sub-poles.
In another aspect of the present invention, the coil is comprised of a flat wire.
In another aspect of the present invention, a gear box is in communication with the axle and the rotor for transmitting torque to the axle and to allow the axle to rotate at a lower rotational speed than the rotor.
In another aspect of the present invention, the gear box has, approximately, a 3 to 1 ratio allowing the axle to rotate at a third of the speed of rotation as the rotor.
In another aspect of the present invention, the rotor has a plurality of vanes disposed on an inside surface of the rotor, wherein the vanes draw air into the device as the rotor is rotating to cool the device.
In another aspect of the present invention, the rotor further comprises a pair of rotor end plates which enclose a first and second end of the rotor.
In another aspect of the present invention, the pair of rotor end plates include a plurality of vent holes for drawing air into and cool the device.
Further aspects, features and advantages of the invention will become apparent from consideration of the following erudite description and the appended claims when taken in connection with the accompanying drawings.